Steve Mills and his wife have one daughter. They previously owned two coffee/ice cream shops, currently operate an internet sales company and teach classes, but his primary job involves the paper industry worldwide. Hobbies and interests lie in gardening, photography, recorded music and of course, their pets.

Grey rocks hurt our fish?

Does anyone know what "they" might be talking about in this post from freecycle.com? Besides growing to eatin' size, our goldfish seem to be doing quite well using our native "grey" stone.

"I am looking for rocks, the kind you use for a pond. Sand stone or anything else. They said not to use the grey rocks, not sure what they are called but you see them at the dam in Normandy. They do something to the water and it hurts the fish."

Freecycle by the way is a national group, but has locally administered chapters that trade things for free. You can not sell anything, or put in promotional statements, but you offer and can request items for giving away. It seems to be watched closely and is also helping many folks, so you might want to check it out.

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The problem with the lite colored stones are that they tend to allow for the production of moss and alge at a faster rate than a darker stone. If you have a good filteration system and or add water on a regular basis you will not have a problem. Both alge and moss have to have sunlight to grow and when you put a lite colored rock in or around your pond it allows the sunlight to reach a little deeper and reflect light a little more. With that being said the moss and alge will deplete oxygen from the water at a much faster rate than a pool without the moss or alge. In this case a small fountain will help.

I how this is useful information.

Thank you,

Steven

-- Posted by gardendoc41 on Mon, Sep 7, 2009, at 10:11 AM

That certainly makes sense and anyone reading this blog since early spring knows that I fight battles with minute algae bloom that fogs the water until the water lilies have had a chance to spread.

Our dry, hot weather and animals (both wild and domestic) leave me no alternative other than replenishing the water frequently.Guess that helps, but I still grow a healthy crop of moss in my stream area.

My pond bottom is black but the edges have our natural limestone or other grey rock. I am not sure how to solve that, nor for aesthetics am I sure that I wan to, but cutting down the light might be a project for next year.

I have two water falls built into the stream that comes from the filter, so I hope that provides enough oxygen. Have not had any fish kills, but I am starting to give them away to reduce the population. I am sure there comes a point when there are too many.